Prior art weather sealing strips have generally been extruded and separate retainer clips have been used for attaching the extruded weather sealing strips to the periphery of a vehicle window opening. These retaining clips are usually designed so that they can be mounted onto the periphery of the window opening by inserting a portion of the retaining clip into an aperture or slot pierced into the sheet metal defining the window opening. The prior art retainer clips are usually made of a springy, resilient material having separate deformable means for securely retaining a weather sealing strip and for locking the retainer clips into the openings provided in the sheet metal defining the window opening. Conventional extruded sealing strips which are attached to the window opening with separate retainer clips have the disadvantages of requiring the manufacturing, procurement, inventorying and assembly of a plurality of separate components. Another disadvantage with extruded sealing strips is that they generally require additional detail such as end caps which are generally used to cover the exposed ends of an extruded sealing strip to provide for better aesthetics.